package com.demo;

import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class BST<E extends Comparable<E>> {
    private class Node{
        public E e;
        public Node left,right;
        public Node(E e){
            this.e=e;
            this.left=null;
            this.right=null;
        }

    }
    private Node root;
    private int size;
    public BST(){
        root = null;
        size = 0;
    }

    public int size(){
        return size;
    }
    public boolean isEmpty(){
        return size ==0;
    }
    public void add(E e){
        if (root ==null){
            root =new Node(e);
            size++;
        }else
            add(root,e);
    }
    private void add(Node node,E e){
        if (e.equals(node.e))
            return ;
        else if(e.compareTo(node.e)<0 && node.left==null){
            node.left=new Node(e);
            size++;
            return;
        }else if (e.compareTo(node.e)>0 && node.right==null){
            node.right=new Node(e);
            size++;
            return;
        }
        if(e.compareTo(node.e) < 0)
            add(node.left, e);
        else //e.compareTo(node.e) > 0
            add(node.right, e);

    }
    public boolean contains(E e){
        return contains(root,e);
    }
    private boolean contains(Node node,E e){
        if (node ==null)
            return false;

        if (e.compareTo(node.e)==0)
            return true;
        else if (e.compareTo(node.e)<0)
            return contains(node.left,e);
        else
            return contains(node.right,e);
    }
    public void preOrder(){
        preOrder(root);
    }
    private void preOrder(Node node){
        if (node ==null)
            return;
        System.out.println(node.e);
        preOrder(node.left);
        preOrder(node.right);
    }

    //不递归的前序遍历
    public void preOrderNR(){
        if (root ==null)
            return;
        Stack<Node> stack=new Stack<>();
        stack.push(root);
        while (!stack.isEmpty()){
            Node curr=stack.pop();
            System.out.println(curr.e);
            if (curr.right != null)
                stack.push(curr.right);
            if (curr.left != null)
                stack.push(curr.left);
        }


    }


    public void inOrder(){
        inOrder(root);
    }
    private void inOrder(Node node){
        if (node ==null)
            return;
        inOrder(node.left);
        System.out.println(node.e);
        inOrder(node.right);
    }

    public void postOrder(){
        postOrder(root);
    }

    private void postOrder(Node node) {
        if (node ==null)
            return;
        postOrder(node.left);
        postOrder(node.right);
        System.out.println(node.e);
    }

    public  void levelOrder(){
        if (root ==null)
            return;
        Queue<Node> q=new LinkedList<>();
        q.add(root);
        while(!q.isEmpty()){
           Node curr= q.remove();
            System.out.println(curr.e);
            if (curr.left!=null)
                q.add(curr.left);
            if (curr.right!=null)
                q.add(curr.right);

        }
    }

    public E minimum(){
        if (size==0)
            throw new IllegalArgumentException("BST is empty");
        return minimum(root).e;
    }
    private Node minimum(Node node){
        if (node.left==null)
            return node;
        return minimum(root.left);

    }
    public E maximum(){
        if (size==0)
            throw new IllegalArgumentException("BST is empty");
        return maximum(root).e;
    }
    private Node maximum(Node node){
        if (node.right==null)
            return node;
        return maximum(root.right);

    }

    public E removeMin(){
        E ret =minimum();
        root=removeMin(root);
        return ret;
    }
    private Node removeMin(Node node){
        if (node.left==null){
            Node rightNode =node.right;
            node.right=null;
            size--;
            return node;
        }
        node.left=removeMin(node.left);
        return node;

    }

    public E removeMax(){
        E ret =maximum();
        root=removeMax(root);
        return ret;
    }

    private Node removeMax(Node node){
        if (node.right ==null){
            Node leftNode=node.left;
            node.left=null;
            size--;
            return node;
        }
        node.right=removeMax(node.right);
        return node;
    }

    public void remove(E e){
        root=remove(root,e);
    }

    private Node remove(Node node,E e){
        if (node ==null)
            return null;
        if (e.compareTo(node.e)<0) {
            node.left = remove(node.left, e);
            return node;
        }
        else if (e.compareTo(node.e)>0){
            node.right=remove(node.right,e);
            return node;
        }
        else{
            if (node.left==null){
                Node rightNode =node.right;
                node.right=null;
                size--;
                return rightNode;

            }
            if (node.right==null){
                Node leftNode=node.left;
                node.left=null;
                size--;
                return leftNode;
            }

            Node successor = minimum(node.right);
            successor.right = removeMin(node.right);
            successor.left = node.left;

            node.left = node.right = null;

            return successor;


        }
    }
    @Override
    public String toString(){
        StringBuilder res=new StringBuilder();
        generateBSTString(root, 0, res);
        return res.toString();
    }

    // 生成以node为根节点，深度为depth的描述二叉树的字符串
    private void generateBSTString(Node node, int depth, StringBuilder res){

        if(node == null){
            res.append(generateDepthString(depth) + "null\n");
            return;
        }

        res.append(generateDepthString(depth) + node.e + "\n");
        generateBSTString(node.left, depth + 1, res);
        generateBSTString(node.right, depth + 1, res);
    }

    private String generateDepthString(int depth){
        StringBuilder res = new StringBuilder();
        for(int i = 0 ; i < depth ; i ++)
            res.append("--");
        return res.toString();
    }
}
